Locate and open the file flex-market-m2-theme-release-note.txt in the root directory of your Magento installation. This file contains the current version number of your theme.
Identify and download all patch packages with a version number higher than your current one.
Example: If your current version is 1.0.1, download patches for versions 1.0.2, 1.0.3, ..., up to the latest version.
Navigate to the Magento root directory.
Extract all downloaded patch packages in ascending version order (e.g., 1.0.2 → 1.0.3 → 1.0.5 → 1.0.8).
Alternatively, you may use the latest full theme package from ThemeForest: flex-market-m2-vx.x.x-quick-start.zip.
Access your Magento root directory via SSH and run the following commands:
php bin/magento setup:upgrade
php bin/magento setup:di:compile
php bin/magento habi:theme:deploy-styles
php bin/magento indexer:reindex
php bin/magento c:f
Deploy static content for your current theme by following this instruction.